A Review of Watt-Level CMOS RF Power Amplifiers

This paper reviews the design of watt-level integrated CMOS RF power amplifiers (PAs) and state-of-the-art results in the literature. To reach watt-level output power from a single-chip CMOS PA, two main strategies can be identified: use of high supply voltage and use of matching and power combination. High supply voltage limits are closely related to device design in the fabrication process. However, the maximum operating voltage can be improved by amplifier class selection, circuit solutions, and process modifications or mask changes. High output power can also be reached by the use of on-chip matching and power combination, commonly using on-chip transformers. Reliability often sets the limits for the PA design, and PA degradation mechanisms are reviewed. A compilation of state-of-the-art published results for linear and switched watt-level PAs, as well as a few fully integrated CMOS PAs, is presented and discussed.